| 摘要 |
PURPOSE:To prevent overcooling and decrease in exhaust gas temperature when cooling a bearing portion on a turbine side of a turbocharger by means of an engine cooling water, by introducing the engine cooling water heat-exchanged by cooling an engine associated fluid to a water jacket of the turbocharger. CONSTITUTION:When a water pump 10 is operated by starting an engine, a cooling water is fed through a bypass passage bypassing a heat exchanger 3 to an engine body 2, and is circulated in the engine body 2 until temperature of the cooling water reaches valve opening temperature of a thermostat provided near the upstream end of a second cooling water passage 9. When the cooling water temperature exceeds the valve opening temperature, the cooling water is circulated between the engine body 2 and the heat exchanger 3 through first and second cooling water passages 8 and 9. A part of the cooling water flowing through a cylinder block 2b located in the course of a circulation passage of the cooling water is introduced into a third cooling water passage 11. The cooling water in the passage 11 is fed through an upstream passage 11a, cooler 7, intermediate passage 11b, water jacket of the turbocharger 4 and downstream passage 11c to the first cooling water passage 8.
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